With an Accessory Drive
John B. Shadle, CMC
John B. Shadle, CMC
A nice old Boley watchmaker's lathe, made in Germany long ago. I've just recently finished "modernizing" it with a DC motor drive, powered by an adjustable pulse-width-modulation power supply. Such a power supply allows you to make wide speed adjustments without losing torque at lower speeds.
It's also set up so that the motor can be shifted. The black screw knobs below the motor cover 1" holes in the oaken motor base. Jockeying the motor will permit aligning the step pulleys on the lathe and motor to make aditional speed and torque changes. The belt is a miniature V-belt, which has remarkable gripping ability -- far more than the usual round plastic or leather belts. The step pulley on the motor is a Taig lathe pulley. The green top is heavy steel.
I've also added an accessory drive to the lathe, shown on the left. The accessory drive uses a separate motor mounted to a base. It drives a belt arrangement which loops over pulleys to drive the watchmaker's pivot polisher mounted on the lathe bed, shown on the right. The belting for the drive is a thin form of green watchmaker's lathe belting.
The height of the upper pulley block is vertically adjustable on the square (keystock) post, which allows great flexibility in ajusting the belt tension and extention. The pulleys can shift sideways on a long shaft to permit moving the pivot polisher in and out without losing the belt.
The accessory drive motor (a common sewing machine motor) is also powered by a small PWM DC drive. This little power supply is a Dayton, available from WW Grainger, as is the motor.
The accessory drive is mounted to a magnetic base, usually used to clamp machinist's measuring tools to a machine tool (available from ENCO and other tool supply houses). The magnet clamps to the steel of the lathe base and it's very strong, but releases easily with a lever. This makes it possible to move the drive for adjustment.
The pivot polisher can be rotated on its base, which requires changing the orientation of the accessory motor assembly.
The pivot polisher is likely 100 years old, a Webster-Whitcombe. I doubt if such wonderful little mechanisms are made any more.
The motor and controller came from Surplus Center in Lincoln, NE. Sometimes they have suitable motors and circuit boards, sometimes not.